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Updated: Jul 16, 2026

Sperm Collection and Computer-Assisted Sperm Analysis in the Teleost Model Japanese Medaka (Oryzias latipes)
Published on: October 6, 2022
DMY gene induces male development in genetically female (XX) medaka fish
Masaru Matsuda1, Ai Shinomiya, Masato Kinoshita
1Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Kawaguchi 332-0012, Japan.
Abstract:
Although the sex-determining gene SRY/Sry has been identified in mammals, homologues and genes that have a similar function have yet to be identified in nonmammalian vertebrates. Recently, DMY (the DM-domain gene on the Y chromosome) was cloned from the sex-determining region on the Y chromosome of the teleost fish medaka (Oryzias latipes). DMY has been shown to be required for the normal development of male individuals. In this study, we show that a 117-kb genomic DNA fragment that carries DMY is able to induce testis differentiation and subsequent male development in XX (genetically female) medaka. In addition, overexpression of DMY cDNA under the control of the CMV promoter also caused XX sex reversal. These results demonstrate that DMY is sufficient for male development in medaka and suggest that the functional difference between the X and Y chromosomes in medaka is a single gene. Our data indicate that DMY is an additional sex-determining gene in vertebrates.
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